Thyroglobulin biosynthesis in a larval (ammocoete) and adult freshwater lamprey (Lampetra planeri Bl.).

1. The biosynthesis of 18-19S thyroglobulin has been studied in a larval and adult freshwater lamprey (Lampetra planeri Bl.). 2. In vivo and in vitro experiments have been performed by injecting into the coelomic cavity or by incubating branchial region labeled constituents of Tg of higher vertebrates (125I, [3H]leucine and various [3H]carbohydrates). 3. Larvae (ammocoetes) and adults incorporate all labels into thyroglobulin (18-19S Tg), containing a small proportion of labeled T3 and T4, as identified by paper chromatography, and very minute amounts of stable iodine. 4. In adults, the biosynthesis of 18-19S Tg proceeds much more rapidly and the labels are incorporated in higher percentage than in larvae. 5. The demonstration of the biosynthesis of the specific thyroid protein, 18-19S Tg, in larvae indicates that the biochemical mechanism of hormonogenesis is present in larval endostyle before the morphological differentiation of thyroid cells and follicles occurring during metamorphosis. 6. Some 18-19S Tg is apparently stored in the endostyle.     

A mouse model for poliovirus neurovirulence identifies mutations that attenuate the virus for humans.

A mutation in the genome of poliovirus type 3 that is known to reduce neurovirulence in humans similarly reduces neurovirulence in mice when incorporated into a mouse-adapted-human poliovirus recombinant. Viral recombinants with a uracil at nucleotide position 472 in the 5'-noncoding regions of their genomes are unable to replicate in the mouse brain. Viral recombinants with a cytosine at this position are neurovirulent in mice. Neurovirulence of poliovirus in mice may therefore prove to be a useful indicator of the genetic stability of new attenuating mutations created by site-directed mutagenesis.     

Defensive strategies of soft corals (Coelenterata: Octocorallia) of the Great Barrier Reef

Summary The relationship between ichthyotoxicity and predation-related defensive functional morphology was examined in alcyonacean soft corals of the central and northern regions of the Great Barrier Reef (GBR), Australia. Approximately 170 specimens were assessed encompassing a number of genera within three families: 1) the Alcyoniidae (Lobophytum, Sarcophytum, Sinularia, Cladiella, Parerythropodium, and Alcyonium); 2) Neptheidae (Lemnalia, Paralemnalia, Capnella, Lithophyton, Nephthea, Dendronephthya, Scleronephthya, and Stereonephthya), and 3) Xeniidae (Anthelia, Efflatounaria, Cespitularia, Heteroxenia, and Xenia). Ichthyotoxicity data were derived from earlier studies which used Gambusia affinis Baird and Girard (Vertebrata, Pisces) as a test organism. These data were compared to morphological data collected from specimens in the field and laboratory. Three sets of statistical analyses were performed, each considering a progressively narrower group of taxa. The first included 68 specimens and considered 16 morphological characters in each, falling into the general categories of gross colony form, colony texture, presence of mucus, colony color, polyp retractility, and sclerite morphology and distribution. These were tested for independence against ichthyotoxicity data. The second set of analyses involved a more restricted morphological data set derived from 28 species of Sinularia in combination with 28 species within the Nephtheidae, comparing them to their respective toxicity ranks. The third analysis considered the previous two taxonomic groups separately in relation to their toxicity levels.The attempt to consider many morphological characters in a taxonomically diverse collection did not reveal any general association in the Alcyonacea between defensive morphology and toxicity, and those associations which did emerge were clearly erroneous. The second analysis, considering only Sinularia spp. and nephtheids, demonstrated a negative association between ichthyotoxicity and the morphological characters of a) polypary armament, b) microarmament of the individual polyp, and c) strong mineralization of the coenenchyme. The third analysis revealed that the negative association found between toxicity and the first two characters was derived entirely from the nephtheids while the association detected between toxicity and the third character was restricted to Sinularia. It is concluded that a relationship between toxicity and morphology can be demonstrated, but it is heavily dependent upon which specific morphological characters are being considered and at what level of taxonomic resolution the analysis is being performed. An approach utilizing many characters over many taxa is unlikely to yield significant, reliable, or meaningful results.Australian Institute of Marine Science Contribution Number 383     

Nucleic acids in mummified plant seeds: screening of twelve specimens by gel-electrophoresis,molecular hybridization and DNA cloning

Summary Twelve seed specimens of varying ages and from different archaeological sites were analyzed for the presence of polymerized DNA and RNA. Amongst the samples tested, one of Vitis vinifera from an archaeological site in Iran (2,000–3,000 B.C.) was found to be completely devoid of nucleic acids. Zea mais seeds of Precolumbial age from Peru (about 800 A.D.) contained depolymerized DNA and RNA. Samples of Vitis vinifera and Rubus sp. from a Lombard archaeological site (800 A.D.) as well as radiocarbon dated seeds from the site of the Spring Sanctuary near Metaponto (I–IV century B.C.) were found to contain polymerized DNA and rRNA bands. However the electrophoretic properties of the rRNAs in one case and hybridization experiments performed with cloned seed DNA in the other, clearly demonstrated that the polymerized nucleic acids were not of plant origin.     

Structural and electronic properties of the liver fluke hemoglobin heme cavity by nuclear magnetic resonance: hemin isotope labeling

Reconstitution of liver fluke (Dicrocoelium dendriticum) apo-hemoglobin with hemins selectively deuterated at specific positions has permitted the assignment of several heme resonances in the proton nuclear magnetic resonance spectrum of the Met-aquo and Met-cyano forms of the holoprotein. It was established that in the Met-aquo form the meso protons resonate at positions characteristic of a six-co-ordinated in-plane iron. From this, we deduced that the Met-aquo species retains a bound water molecule at pH values as low as 4.5. The orientation of the proximal histidine imidazole ring with respect to the heme group in the cavity was determined through the identification of the heme methyl signals and the analysis of the hyperfine shift pattern in the Met-cyano hemoglobin proton nuclear magnetic resonance spectrum. Compared to sperm whale myoglobin, the heme appears to be rotated by 180 degrees about the alpha, gamma meso-axis. Protein isomers with the heme group in a reversed orientation were not detected, even shortly after reconstitution. In the Met-cyano form, the resonances most affected by the Bohr transition were shown to arise from the heme propionates.     

Actin cytoskeleton in intact and wounded coenocytic green algae

Summary The subcellular distribution of actin was investigated in two related species of coenocytic green algae, with immunofluorescence microscopy. Either no, or fine punctate fluorescence was detected in intact cells of Ernodesmis verticillata (Kützing) Børgesen and Boergesenia forbesii (Harvey) Feldmann. A reticulate pattern of fluorescence appears throughout the cortical cytoplasm of Ernodesmis cells shortly after wounding; this silhouettes chloroplasts and small vacuoles. Slender, longitudinal bundles of actin become evident in contracting regions of the cell, superimposed over the reticulum. Thicker portions of the bundles were observed in well-contracted regions, and the highly-convoluted appearance of nearby cortical microtubules indicates contraction of the bundles in these thicker areas. Bundles are no longer evident after healing; only the reticulum remains. In Boergesenia, a wider-mesh reticulum of actin develops in the cortex of wounded cells, which widens further as contractions continue. Cells wounded in Ca²⁺-free medium do not contract, and although the actin reticulum is apparent, no actin bundles were ever observed in these cells. Exogenously applied cytochalasins have no effect on contractions of cut cells or extruded cytoplasm, and normal actin-bundle formation occurs in treated cells. In contrast, erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA) completely inhibits longitudinal contractions in wounded cells, and few uniformly slender actin bundles develop in inhibited cells. These results indicate that wounding stimulates a Ca²⁺-dependent, hierarchical assembly of actin into bundles, whose assembly and functioning are inhibited by EHNA. Contraction of the bundles and concomitant wound healing are followed by cessation of motility and disassembly of the bundles. The spatial and temporal association of the bundles with regions of cytoplasmic contraction, indicates that the actin bundles are directly involved in wound-induced cytoplasmic motility in these algae.Abbreviations EHNA erythro-9-[3-(2-hydroxynonyl)]adenine - MT(s) microtubule(s)     

Direct adhesion to type I and homotrimer collagens by breast carcinoma and embryonic epithelial cells in culture: a comparative study

A continuous cell line of neoplastic cells derived from ductal infiltrating carcinoma of the human breast (8701-BC), was assayed for its ability to adhere to collagen substrates. The collagens used were regular type I and type I homotrimer isolated from primary breast carcinomas. Comparative studies were performed using an embryonic epithelial cell line derived from human intestine (Int. 407). The neoplastic cells adhere equally well to both collagens, while the embryonic epithelial cells recognized only the homotrimer. Some receptor diversity was recognized in the adhesion of the two cell lines to homotrimer collagen. The data demonstrate a functional difference between type I and homotrimer collagen with regard to cellular recognition and attachment. In addition, the data suggest that oncogenic transformation of breast epithelial cells promotes their adhesive properties to interstitial collagens and that this may be relevant to their increased potential to invade host tissue.